1. Field of the Invention
The present invention relates to a display device for current-driving a light-emitting device provided in each pixel to display an image and a driving method of the same. The present invention also relates to electronic apparatus using such a display device. More specifically, the present invention relates to a driving method of a so-called active matrix display device for controlling the amount of current to be passed through an organic electroluminescence (EL) device or other light emitting device by means of an insulating gate field effect transistor provided in each pixel circuit.
2. Description of the Related Art
A display device such as liquid crystal display has a number of liquid crystal pixels arranged in a matrix. Such a display device displays an image by controlling the transmission or reflection intensity of incident beam for each pixel according to image information to be displayed. This is also true for an organic EL display using organic EL devices. However, an organic EL device is self-luminous unlike a liquid crystal pixel. As a result, an organic EL display device offers several advantages over a liquid crystal display device. Such advantages include high image visibility, no need for backlight and high response speed of the device. Further, the brightness level (gray level) of each light-emitting device can be controlled by controlling the current level flowing through the same device. As a result, an organic EL display differs significantly from a liquid crystal display or other voltage-controlled display in that it is a so-called current-controlled display.
An organic EL display can be either simple (passive)-matrix or active-matrix driven as with a liquid crystal display. The former has some problems although simple in construction. Such problems include difficulty in implementing a large high-definition display device. For this reason, the development of active matrix displays is going on at a brisk pace today. Such displays, described in the documents listed below, control the current flowing through the light-emitting device in the pixel circuit with an active device (typically, thin film transistor or TFT) provided in the same pixel circuit, as is disclosed in Japanese Patent Laid-Open Nos. 2003-255856, 2003-271095, 2004-133240, 2004-029791, 2004-093682 and 2006-215213.